The aim of this pilot study is to evaluate the potential cariogenic effect of various food products on enamel by determining the biochemical changes of plaque fluid. The change in the degree of saturation of calcium phosphate in the extracellular fluid of plaque with respect to enamel following the mastication of a food product is an important determinant of the stabillity of enamel mineral. With the described microanalytical technique one will be able to analyze pH, calcium and phosphate changes in the extracellular fluid of plaque or plaque fluid following a challenge with a particular food product. Twenty individuals equally divided into caries active and caries inactive groups will be given a 10% sucrose rinse and three referenced food products on four separate occasions. Plaque samples on each individual will be collected prior to and at fifteen minute intervals after a sucrose or food product challenge for a period of an hour on each occasion. The plaque sample for each time interval on each individual will be centrifuged and the extracellular plaque fluid will be analyzed for pH, calcium, and phosphorous concentration employing a recently developed microtechnique. The data obtained will enable one to plot the degree of saturation of calcium phosphate in plaque fluid with respect to the enamel mineral versus time for an individual on each procedure. This plot will enable one to perform appropriate statistical tests to discriminate between caries active and caries inactive subjects as well as between food products on the same individual or a group of subjects. A study employing all key parameters of enamel solubility rather than pH alone will hopefully provide data on the effects of various food products in the demineralization of tooth enamel.